Disclosed herein is a toner composition including a toner particle having a surface; a metallic pigment bonded to the surface of the toner particle; and an insulative surface additive disposed over the metallic pigment.
Conventional printing systems for toner applications consist of four stations comprising cyan, magenta, yellow, and black (CMYK) toner stations. Xerox® Corporation is developing printing systems including the concept of a fifth xerographic station to enable gamut extension via the addition of a fifth color or specialty colors. At any given time the machine can run CMYK toners plus a fifth color in the fifth station. To further increase the capability of the new systems and provide novelty printing capability to customers, it is desirable to develop a metallic ink formulation to also be run in the fifth station. Toners capable of making metallic hues, especially silver or golden, are particularly desired by print shop customers for their esthetic appeal, for example, on wedding cards, invitations, advertising, etc. Metallic hues cannot be obtained from CMYK primary color mixtures.
A requirement for achieving a metallic effect is incorporation of a flat reflective pigment in a toner that can reflect light and give the desired metallic effect. Aluminum flake pigments are one possible choice for preparing metallic silver toner due to their commercial availability and low cost. However, there are challenges regarding use of aluminum flake pigments to create metallic hue silver toners. For example, such toners may possess a low charge due to increased conductivity of the aluminum pigment. It is difficult to incorporate large aluminum metal flake pigment into toner. It is also difficult to optimize the orientation of aluminum flake pigment in order to achieve maximum metallic hue. Further, there are safety concerns with processing and handling of explosive aluminum powders. For example, in preparation of toner by conventional processes including melt mixing pigment into resin followed by grinding, classification, and additive blending, there is a danger of sparking from the conductive aluminum during the grinding step.
Thus, while currently available toners and toner processes are suitable for their intended purposes, there remains a need for an improved metallic toner and process for preparing same. There further remains a need for a viable process for preparing silver metallic toner.
The appropriate components and process aspects of the each of the foregoing U. S. Patents and Patent Publications may be selected for the present disclosure in embodiments thereof. Further, throughout this application, various publications, patents, and published patent applications are referred to by an identifying citation. The disclosures of the publications, patents, and published patent applications referenced in this application are hereby incorporated by reference into the present disclosure to more fully describe the state of the art to which this invention pertains.